Bundle a static x264 in the prebuilt archives

.github/workflows/binaries.yml

@@ -69,13 +69,30 @@ jobs:
 
       - name: Install dependencies (macOS)
         if: runner.os == 'macOS'
-        run: brew install nasm pkg-config x264 x265
+        run: brew install nasm pkg-config x265
 
       - name: Install dependencies (Linux)
         if: runner.os == 'Linux'
         run: |
           sudo apt-get update
-          sudo apt-get install -y --no-install-recommends nasm pkg-config clang libx264-dev libx265-dev
+          sudo apt-get install -y --no-install-recommends nasm pkg-config clang libx265-dev
+
+      # x264 puts its ABI version in its symbol names (x264_encoder_open_165), so an FFmpeg
+      # compiled against the runner's x264 doesn't link with the x264 of another system. The
+      # archive carries its own static x264 instead, which the linker finds before the system's.
+      - name: Compile x264
+        if: contains(matrix.features, 'x264')
+        env:
+          X264_REV: b35605ace3ddf7c1a5d67a2eb553f034aef41d55 # stable, 0.165.3222
+        run: |
+          git init -q x264
+          git -C x264 fetch -q --depth 1 https://code.videolan.org/videolan/x264.git "$X264_REV"
+          git -C x264 checkout -q FETCH_HEAD
+          cd x264
+          ./configure --prefix="$GITHUB_WORKSPACE/external" --enable-static --enable-pic --disable-cli --disable-opencl
+          make -j"$(getconf _NPROCESSORS_ONLN)" install-lib-static
+          echo "PKG_CONFIG_PATH=$GITHUB_WORKSPACE/external/lib/pkgconfig" >> "$GITHUB_ENV"
+          echo "FFMPEG_BINARIES_BUNDLE_LIBS=$GITHUB_WORKSPACE/external/lib/libx264.a" >> "$GITHUB_ENV"
 
       - name: Compile FFmpeg
         run: cargo build --release --target ${{ matrix.target.triple }} --features "build,static,build-portable,${{ matrix.features }}"

README.md

@@ -15,13 +15,16 @@ build script first downloads a static FFmpeg matching the target and the enabled
 the [`binaries-<version>` release](https://github.com/dmtrKovalenko/rust-ffmpeg-sys/releases)
 and only compiles FFmpeg from source when there is none. Archives are built by
 `.github/workflows/binaries.yml` for macOS (arm64, x86_64) and Linux (x86_64, arm64) with the
-codec sets fframes uses. External codec libraries (x264, x265) still come from the system.
+codec sets fframes uses. They carry a static x264, because x264 puts its ABI version in its
+symbol names and an FFmpeg compiled against one x264 doesn't link with another. x265 still
+comes from the system.
 
 - `FFMPEG_FORCE_BUILD=1` always compiles from source (so do `FFMPEG_MARCH`/`FFMPEG_MTUNE`, the
   archives are compiled with `build-portable`).
 - `FFMPEG_BINARIES_URL` overrides the download URL template (`{tag}`, `{key}`; `file://` works).
 - `FFMPEG_BINARIES_CACHE` is where downloads are kept (default: the user cache directory).
 - `FFMPEG_BINARIES_EXPORT_DIR` makes a source build write its archive there.
+- `FFMPEG_BINARIES_BUNDLE_LIBS` lists static libraries an exported archive carries in `lib/`.
 
 ## Feature flags
 

build_prebuilt.rs

@@ -17,6 +17,10 @@
 //!   directory), so that every project on the machine downloads them once.
 //! - `FFMPEG_BINARIES_EXPORT_DIR`: after compiling from source, write the archive and its key to
 //!   this directory (used by CI to produce the binaries).
+//! - `FFMPEG_BINARIES_BUNDLE_LIBS`: static libraries (a path list, like `PATH`) that are copied
+//!   into the archive's `lib/` on export. CI bundles x264 this way: its ABI version is part of
+//!   its symbol names (`x264_encoder_open_165`), so an FFmpeg compiled against one x264 doesn't
+//!   link with another, and the system's x264 differs from machine to machine.
 //!
 //! Archives are compiled with the `build-portable` flags, so setting `FFMPEG_MARCH` or
 //! `FFMPEG_MTUNE` compiles from source as well.
@@ -39,6 +43,7 @@ pub fn rerun_if_env_changed() {
         "FFMPEG_FORCE_BUILD",
         "FFMPEG_BINARIES_CACHE",
         "FFMPEG_BINARIES_EXPORT_DIR",
+        "FFMPEG_BINARIES_BUNDLE_LIBS",
         "FFMPEG_MARCH",
         "FFMPEG_MTUNE",
     ] {
@@ -203,6 +208,15 @@ pub fn export(dist: &Path) -> io::Result<()> {
         return Ok(());
     };
     fs::create_dir_all(&export_dir)?;
+    // Next to FFmpeg's own libraries, the linker finds them before the system's.
+    if let Some(libs) = env::var_os("FFMPEG_BINARIES_BUNDLE_LIBS") {
+        for lib in env::split_paths(&libs) {
+            let name = lib
+                .file_name()
+                .ok_or_else(|| io::Error::other(format!("{} is not a library", lib.display())))?;
+            fs::copy(&lib, dist.join("lib").join(name))?;
+        }
+    }
     let key = key();
     run(Command::new("tar")
         // pkg-config files hold absolute paths of the build machine